Multiple choice

The mean of 100 observations is 20 if a number 45 is mistaken as 54 find the correct mean

  1. 19.91

  2. 20.91

  3. 20.09

  4. 19.09
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A Correct answer
Explanation

Original sum = 100 * 20 = 2000. Correct sum = 2000 - 54 + 45 = 1991. Correct mean = 1991 / 100 = 19.91.

AI explanation

The incorrect sum of the 100 observations is 100 multiplied by 20, which equals 2000. The correct sum is found by subtracting the wrong value and adding the actual value, giving 2000 minus 54 plus 45, which equals 1991. Dividing this correct sum by 100 yields the correct mean of 19.91.

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